Method of shaping superconducting oxide material

ABSTRACT

A method of forming a superconducting oxide material comprises the steps of forming of a superconducting oxide material into a thin film on a film-forming surface portion, creating a plasma to form an activated oxygen atmosphere, subjecting the thin film to a magnetic field through the thickness of the thin film, thereby injecting the activated oxygen into the thin film so that crystals of the superconducting oxide material are aligned parallel or perpendicular to the film-forming surface portion.

This is a continuation application of Ser. No. 07/564,681 filed Aug. 7,1990, now abandoned, which is a continuation application of Ser. No.07/252,591 filed Oct. 3, 1988, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a superconducting oxide material, andspecifically a process for manufacturing a superconducting oxide ceramicmaterial film, wherein crystals are uniformly aligned in a directionperpendicular or parallel to a surface portion on which the thin film isformed.

2. Description of the Related Art

Recently, superconducting ceramic materials have been attracting a greatdeal of attention. These materials were first reported by IBM's ZurichLaboratories in the form of Ba-La-Cu-O (BALACUA) type high temperaturesuperconducting oxide material. In addition, the YBCO (YBa₂ CuO₆₋₈)types are also known. However, these types could be prepared only bymixing and firing various types of oxide powders to form tablets, sothat even when a Tc onset of 90K was obtained, a sufficiently thin filmwas not possible. In addition, it was completely unknown that the thinfilm forward at a lower temperature can have crystal grains uniformlyoriented in a direction with reference to the surface portion on whichthe film is formed (which is hereinafter referred to as the film-formingsurface portion).

The critical current density of these superconducting materials withpolycrystalline oxide structure in tablets is small. In order to correctthis problem, it is desired that all the ab surfaces of the crystalgrains (also referred to as the C surface, the surface perpendicular tothe c axis direction) be mutually oriented.

Furthermore, it is strongly desired that the Tco (temperature at whichresistance is zero) of the superconducting oxide material be higher. Itis desirable that operation be possible at the temperature of liquidnitrogen (77K) or a higher temperature, and that, in turn, the Tcotemperature of 90K or higher be available in the structure of the thinfilm.

In addition, there is no means of performing oxygen treatment at lowertemperature that will reach into the interior without damaging thesurface; also, in the case of a porous superconducting material, even ifannealing is possible there has not been any means of performing, in ashort time, oxide annealing of single crystals or a closely similarmaterial which have been adequately oriented.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a method of producinga superconducting oxide material with which a device utilizing crystalanisotropy is easily produced.

Another object of the present invention is to provide a method ofproducing a superconducting oxide material having a large criticalcurrent density.

These objects are accomplished in the present invention by the provisionof a process of converting an oxidizing gas to plasma, applying amagnetic field to the film-forming surface portion, and subjecting thefilm to magnetism, heat and plasma annealing, thereby causing crystalrealigning.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features, and advantages of the presentinvention will become more apparent from the following description ofthe preferred embodiments taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram showing one example of the crystal structure of thesuperconducting oxide material used in the present invention.

FIG. 2 is a diagram showing a microwave plasma annealing device withmagnetic field applied used in this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to improve the superconducting characteristics of an oxidesuperconducting material, particularly in a thin film, an oxidizing gasis converted to plasma, for example by microwaves in the presentembodiments; at the same time a magnetic field is applied to thefilm-forming surface portion. The combination of magnetism, heat andplasma annealing causes the crystal to realign during annealing.

Specifically, a method of forming a superconducting oxide material inthe present embodiments comprises the steps of forming of asuperconducting oxide material into a thin film on a film-formingsurface portion, creating a plasma to form an activated oxygenatmosphere, subjecting the thin film to a magnetic field through thethickness of the thin film, thereby injecting the activated oxygen intothe thin film so that crystals of the superconducting oxide material arealigned in a predetermined direction with reference to the film-formingsurface portion.

More specifically, in order to achieve higher critical current densityin this invention, activated oxygen such as O or O₃, which is producedat very high efficiency in a microwave plasma, is used as an annealinggas in the magnetic field plasma annealing for thin film forming. Thisactivated gas is injected into the interior through a magnetic field.That is, since the magnetic field penetrates into the interior of thesuperconducting material, as long as this activated plasma remainsactivated it penetrates into the interior along magnetic field lines.For this reason, whereas in the previously well-known simple plasmaannealing method, after the activated oxygen arrives at the surface ofthe material, it penetrates into the interior only by thermal diffusion,in the method of this invention, annealing takes place by the 10 timesfaster injection speed in bulk (in the interior). In addition, toprevent the surface being treated from being sputtered (damaged) whichwould cause the characteristics of the oxide superconducting material todeteriorate, when this annealing method is used, neither sputtering noreither low frequency (1 KHz to 15 MHz) or high frequency (for example13.56 MHz) plasma CVD is carried out; the frequency is increased intothe microwaves region (500 MHz to 10 GHz, typically 2.45 GHz), so thatwhen the plasma is produced, kinetic energy is not imparted to eitherthe reactive gas or the particles.

It is possible to produce a material consisting of superconducting oxidematerials by other methods, such as sputtering, spraying, CVD andprinting. Sometimes in these methods, amorphous structures can beobserved at an initial stage. In order to produce such a material, thea, b or c axis of crystals having a deformed perovskeit structure asshown in FIG. 1 is aligned parallel or approximately parallel to adesirable direction corresponding to its use, and the magnetic fieldused to produce the plasma is used at the same time. It is possible withthis magnetic field to realign the crystal array plane in a fixeddirection to produce magnetic axial growth. In addition, in the case inwhich a single crystal is grown, magnetic epitaxial growth occurs. Thisinvention takes thin film materials and tablet materials produced by theprevious methods and applies a magnetic field continuously to anneal thematerial, producing a realignment in the direction of the magneticfield. A magnetic field of 0.1 Tesla (T) or more which penetrates thematerial is used to cause annealing to take place while the magneticfield is applied continuously in the desired direction, in a highlydense plasma produced in activated oxygen or a gas containing activatedoxygen. This permits the film orientation to be aligned in a directionwhere the magnetic field and the c axis are aligned.

A representative superconducting oxide material used in the presentinvention is an oxide using elements in Group IIa and Group IIIa of thePeriodic Table and copper.

The superconducting material of the present invention can be generallyrepresented by the expression (A_(1-x) B_(x))_(y) Cu_(z) O_(w), wherex=0.1 to 1, y=2.0 to 4.0, preferably 2.5 to 3.5, z=1.0 to 4.0,preferably 1.5 to 3.5, and w=4.0 to 10.0, preferably 6 to 8. Onerepresentative example is a material having a modified or deformedperovskeit structure represented by the expression AB₂ Cu₃ O₆₋₈. A is atleast one member selected from the yttrium group and the otherlanthanoids. The yttrium group is defined as the group containing Y(yttrium), Gd (gadolinium), Yb (ytterbium), Eu (europium), Tb (terbium),Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Lu (lutetium),Sc (scandium), and other lanthanoids - Physics and Chemistry Dictionary(Iwanami Shoten, published Apr. 1, 1963).

B is at least one member selected from the group of Ba (barium), Sr(strontium) and Ca (calcium).

The superconducting oxide material illustrated in the present inventionhas the crystal structure as shown in FIG. 1, which is a modified ordeformed perovskeit structure. It has a plane including copper (2) andits neighboring oxygen (5), and other planes including copper (3),oxygen (6) positioned next to it, and oxygen vacancy (7), and includingcopper (2') and oxygen (5'). It has an element (1) from Group IIIa ofthe Periodic Table, for example Y, and an element (4) from Group IIa ofthe Periodic table, for example, Ba.

The inventor of the present invention, suggests as the mechanism whichcreates superconductivity, that by means of the mutual action of oxygen(5), (5') having a layer structure, and copper (2), (2') which is at thecenter of the layer, electrons which are paired (electron pair) shiftthe surface (the surface formed at the ab axes, specifically the surfaceparallel to the C surface). Up to this time, mutual action with a phononwas considered to be the cause of the formation of the paired electrons,based on the BCS theory.

However, the inventor of the present invention hypothesizes a theorythat a quasiparticle known as a magnon is created when upper and loweroxygen vacancies (7) between which this laminar structure is sandwiched(the other vacancy exists in the atomic system which is positioned onthe upper or lower side of the diagram) are associated with each otheror with a rare earth element (1) which is a screw magnetic body, andthat the quasiparticle acts as an intermediary to form a pair ofelectrons spinning in opposite directions. Specifically, the magnonfluctuates in the c axis direction in the drawing (the fluctuation ofthe magnon in the direction perpendicular to the ab surface is bestreflected in the electron pair), and this magnon, which draws one of theelectrons in pair having spinning in mutually opposite directions, isrepelled by the other. The magnon not completely in evidence but worksbehind the scenes, and the electron pairs shift in the directionparallel to their respective a - b axes in a surface with a laminarstructure (surface made from (2), (5) and surface made from (2'), (5')).This can be considered as the cause of superconductance. In addition, itis possible to consider that the fluctuation of the oxygen vacancy isthe fluctuation of the phonon, and therefore to have a pattern whichsupplements the BCS therory, in which it can be considered that thephonon, through the medium of the magnon, indirectly causes the electronpair to form.

Since the magnetic field has a strong effect on the action describedhere, it can be expected that when the magnetic field is applied inannealing, it will affect the crystal orientation. This annealing isdone in an atmosphere in which a plasma has been created by the mutualinteraction of the magnetic field and electric field; in addition, themagnetic field used to produce the plasma is applied to the materialbeing annealed. The film-forming surface portion is aligned eitherparallel or perpendicular to the magnetic field in the region where themagnetic field is strong to align all of the crystals in a specifieddirection during annealing.

In addition, by also applying a microwave electric field in a directionperpendicular to this magnetic field, that is to say in the ab plane inwhich the electric current flows when the material is superconducting,this alignment is made easier. In particular, by applying the electricand magnetic fields in such a way that they mutually interact, mixedcyclotron resonance occurs making it possible for the plasma to beproduced not at the low pressures of 10⁻³ to 0.1 torr familiar in theplasma CVD method and the ECR (electron cyclotron resonance) method, butat a very high pressure of 1 to 800 torr, at which a high density plasmais produced. By more completely reacting the reactive gas or reactiveparticles with the activated oxygen, the reaction products are oriented,so that the c axis is aligned with the magnetic field. For this reason,the reaction products gradually accumulate on the film-forming surfaceportion with the c axes of the reaction products oriented along themagnetic field. In consequence it becomes possible to create films withless restriction on the type of substrate. Another desirable feature ofthis method is that by applying a magnetic field while the material isbeing heated, a polycrystalline film can be grown such that thepolycrystal axes are aligned or approximately aligned with each other.By using a substrate that has crystal directions with its orientationaxis aligned with the growth plane, magnetic epitaxial alignment is doneat low temperature, wherein the thin film is formed with single crystalalignment.

In this case, the superconducting oxide material having a single crystalstructure is obtained at a lower temperature. The critical currentdensities along the C plane in FIG. 1 are larger than those normal tothe C plane by two or much orders of magnitude. For this reason, whenusing polycrystals, it is extremely important that polycrystals havingscattered crystal orientations be arranged to have the crystal axispositioned in one direction in order to obtain a high critical currentdensity.

In this invention, when the film formed is subjected to a magnetic fieldand heat annealing by applying a magnetic field of 0.1 Tesla (T) ormore, typically 0.3 T to 5 T, in the intended c-axis direction, most orall of the crystals, that is to say polycrystals are grown, having theirc-axes aligned in the direction in which realignment is to take place,which is the same as or close to the magnetic field direction. Inaddition, by applying a microwave electric field in a directionperpendicular to this magnetic field, in the ab plane, it is made eveneasier to align the crystal c axes with the magnetic field.

In this way one crystal particle developing into a polycrystal in aninitial amorphous structure can become larger even if it is composed offine particles each having a grain size of 10 to 1000 Å. In turn,because adjacent crystals have substantially the same crystal axis incommon, the barrier and the blow hole at the crystal boundary have moreof a tendency to disappear, and a structure equivalent to the singlecrystal can be obtained. Then, the respective crystals can all becomeadjusted at the ab surface (the surface perpendicular to the c axis). Asa result, by the method of the present invention, the critical currentdensity, which up to the present has been 10² A/cm² (77K) in the case ofrandom crystal orientation, increases up to 10⁴ to 10⁶ A/cm² (measuredat 77K) with the current flowing parallel to the ab surface, and canbecome equal in density to a single crystal or at least close to aboutthe 1/5 level. Then, it becomes easier to make a thin film of the singlecrystal structure of large area, which is ideal for a superconductingoxide material.

In this invention, a magnetic field has been applied in the verticaldirection or horizontal direction with respect to a superconducting filmhaving a certain axis alignment; additionally applying a microwaveelectric field perpendicular to the magnetic field to generate activatedoxygen is effective in lowering the annealing temperature.

In addition, the crystal axis of the substrate which has thefilm-forming surface portion is effectively adjusted by the magneticfield, conforming to the direction of arrangement of the crystals. Forexample, the crystal substrate (100) of MgO (magnesium oxide), SrTiO₃(strontium titanium oxide), and YSZ (yttrium stabilized zircon) can beused, and a magnetic field applied in the direction perpendicular to thefilm-forming surface portion to create a film, so that the ab surfacecan be formed parallel to the film-forming surface portion. In addition,using these crystal substrates which have a (110) surface, when amagnetic field is applied parallel to the film-forming surface portionfor film-forming and annealing, it is possible to obtain the ab surfaceformed in the direction perpendicular to the film-forming surfaceportion during heat and magnetic field annealing. Then it is possible toobtain a thin film of a single crystal or of polycrystals close to thesingle crystal.

EMBODIMENT NO. 1

Now referring to FIG. 2, this drawing shows the magnetic field assistedmicrowave plasma annealing device used in the present invention to carryout the formation of the superconducting oxide material and the magneticfield and heat annealing after the formation.

The device in this drawing comprises a plasma generating chamber 31which can be maintained at atmospheric pressure or at a reducedpressure, an auxiliary space 12, a cylindrical electromagnet 15 whichgenerates a magnetic field, a power source 35 for the electromagnet 15,a microwave oscillator 14, a vacuum pump 26 and a rotary pump 24 for anexhaust gas system, a pressure adjusting valve 19, a substrate holder10', a substrate 10 having a film-forming surface portion, a microwaveintroduction window 39, a plurality of gas systems 16, 17, a pluralityof water cooling systems 28, 28', a rod 29 for removing the substrateand substrate holder, an da plurality of water cooling systems 27, 27'for cooling and maintaining a film-forming surface portion at a suitabletemperature through the inside of the rod.

The substrate holder 10' is provided with a buffer layer 21, 21' and acooling layer 22 to convert the substrate surface which has overheatedfrom the plasma in the plasma generating chamber 31 to a suitabletemperature, and to maintain the substrate surface at a specifiedtemperature, for example, 200° to 500° C. The cooling layer 22 is formedfrom iron, nickel, or cobalt, all of which are ferromagnetic materials,and one part is hollow to allow circulation of the cooling water in thesystem 27, 27'. The buffer layer 21, 21' is formed of a non-magnetic,heat resistant material such as ceramic, stainless steel, or glass. Thecooling layer 22 of the ferromagnetic member strengthens the magneticfield at the surface of the substrate, and in order to avoid having itreduced to paramagnetism from overheating, it is shielded from heat bythe buffer layer 21, 21'.

First, the substrate 10 having a superconducting oxide material is seton the substrate holder 10', and this system is positioned in the plasmagenerating chamber 31 through a gate valve 11. In this embodiment of thepresent invention, the MgO, SrTiO3 or YSZ type with a (100) or (110)surface is used as a substrate, and silicon wafer, a glass substrate,platinum substrate or other ceramics which has an insulating film formedfor IC on a portion of its top surface, and a superconducting oxidematerial of YBa₂ Cu₃ O_(w) (w=6 to 10) disposed on a metal such assilver are also used as a substrate.

When operating at atmospheric pressure, the valve 19 is closed and thevalve 23 opened. In addition, when operating under reduced pressure, thevalves 19 and 25 are opened and the valve 23 is closed, and the vacuumpump 26 and the rotary pump 24 may be operated.

In the manufacturing process, a vacuum of 1×10⁻⁴ or less is firstapplied to the entire system using the mechanical booster (vacuum) pump26 and the rotary pump 24. Next, a non-product gas (this is an oxidizinggas which does not itself form a solid body after a decompositionreaction), N₂ O, NO, NO₂, air or oxygen, for example, the oxygen (6) ispassed through the 2000 SCCM gas system 16 and introduced into theplasma generating chamber 31 where it is pressurized to 30 torr. Anexternal microwave of 500 MHz or greater, for example a microwave 30-2of a frequency of 2.45 GHz, is applied form the microwave oscillator 14at a strength of 0.5 to 5 KW, for example, 1.5 KW. In addition, by usinga magnet 15 water-cooled as shown by 18, 18', magnetic field 30-1 isapplied, wherein an electric current flows through the magnet 15 toobtain a magnetic field of about 1 T at the surface of the substrate 10,and a high density plasma with mixed cyclotron resonance is generated inthe plasma generating chamber 31. At this time a magnetic field 30-1 andan electric field 30-2 are mutually at right angles. In the drawing, themagnetic field 30-1 is applied perpendicular to the film-forming surfaceportion. By means of this high density plasma, activated oxygen atalmost 100% ionization can be created. Superconducting oxide materialse.g. those conforming to (A_(1-x) B_(x))Cu_(z) O_(w), is formed on thesubstrate 10 by a sputtering method, electron beam evaporation, spraymethod, or screen printing method in this embodiment.

When mixed cyclotron resonance is obtained by mutual utilization ofmicrowave energy and a magnetic field, the plasma temperature is muchhigher than 1150° C. (the melting temperature of the superconductingoxide material), being as high as the 3000° to 10,000° C. range,whereupon the reactive atoms are formed on the film-forming surfaceportion in the inherent crystal structure. A thin film of thissuperconducting oxide material can be accumulated on the film-formingsurface portion of the substrate 10 on the substrate holder 10' which iscooled to a low temperature by the cooling layer 22 so that thetemperature of the substrate itself is in the low range of 200° to 500°C.

Then, by annealing at 400° C. for about three hours in the magneticfield after the film is formed, it is possible to form a thin filmsuperconducting oxide material by virtue of modification thereof with amodified perovskeit structure of rhombic crystals with a thickness of 1μm to 1 mm as indicated in FIG. 1, wherein twins are rarely observed inthe modified or deformed film. There is a twin phase boundary observedevery 200 to 1000 Å in the conventional thin film not in the modified ordeformed structure.

In FIG. 2, one ring-shaped magnet 15 is used for generating the magneticfield 30-1.

In the plasma generating chamber 31 there is also a region (within 875gauss±185 gauss) which has mutual action between an electric field and amagnetic field, and there are many other regions which have an evengreater magnetic strength.

Then, the substrate 10 is positioned in the region which has the maximummagnetic field (here, it is the section centered around the magnet 15).Therefore, in the case of the arrangement shown in FIG. 1, the magneticfield 30-1 is applied perpendicular to the film-forming surface portionon the substrate, and the electrical field 30-2 is applied parallel tothat surface. The strength of the magnet is controlled in order tocreate a region of 875 gauss which satisfies mixed cyclotron resonancein the space between the film forming surface in the plasma generatingchamber 31 and the nozzle 34 for introducing the gas.

The material for producing the oxide superconducting film is formed intoa film on the film-forming surface portion of the substrate in thedirection of the magnetic field along the c axis through the activateddissociation reaction in the area of mixed cyclotron resonance.

The critical current density of the superconducting oxide film made atthis time was measured at 11.2×10⁵ A/cm² parallel to the substratesurface.

Specifically, the crystal structure shown in FIG. 1 was sufficientlyformed at the time the film was formed and in the subsequent annealing.Also, it was apparent from the results of X-ray analyses that the c axiswas formed in the direction parallel to the magnetic field,specifically, in the direction perpendicular to the film-forming surfaceportion.

EMBODIMENT NO. 2

In general this embodiment uses a substrate of superconducting materialin tablets having constituents of the form YBa₂ Cu₃ O_(6to8) or YBaSrCu₃O_(6to8). In advance of a magnetic-heat annealing of a substratecontaining a superconducting oxide material for 15 hours in a microwaveplasma activated oxygen atmosphere at 300° C. to 950° C., the substrateis set in the device shown in FIG. 2, in order that the c-axis isaligned with the magnetic field (30-1) (having a strength of 0.5 to 3T). A magnetic field of 1 T is applied at 930° C. for 3 hours, followedby gradual cooling at a rate 10° C./minute, then keeping 2 T at 400° C.for 1 hour, then gradual cooling at 10° C./minute until 300° C. isreached, at which point the magnetic field is no longer applied,stopping plasma formation. In addition, an electric field of 10³ to5×10⁴ V/cm (30-2) was applied in a direction perpendicular to themagnetic field. As a result, Tco was increased by about 100K, resultingin 230K to 280K. Also, a critical electric current density of 2.3×10⁴A/cm² was obtained.

In this invention, the material to which magnetic field and heatannealing are applied dose not necessarily have to be in a thin film ortableted form. Depending on market needs it can have the form of a film3 to 30 micrometers thick, a wire of band structure 1 to 5 mm wide and10 to 1000 micrometers thick or a wire coated with silver around itsouter diameter. In any of these cases a magnetic field is applied in thethickness direction to realign the crystals inside the band.

In summary, by the use of the present invention, it has become possibleto create a thin film superconducting oxide material with the crystalaxes uniformly oriented which operates at the temperature of liquidnitrogen or higher, which up to now has been impossible to attain. It isalso possible to make an oriented polycrystal superconducting oxide thinfilm on the surface of the substrate in an amorphous or microcrystallinestructure of glass, silicon oxide, or silicon nitride or the like.

In this invention, a superconducting material that has already beenformed into for example a Josephson element having the desired shape isre-heat annealed in an oxide plasma in a magnetic field at 300° C. orhigher temperature. At the same time a microwave electric field isapplied in the direction in which it is intended for the electriccurrent to flow. A magnetic field is added in the c-axis direction; thisis effective in aligning the crystals in one direction.

Superconducting ceramics for use in accordance with the presentinvention also may be prepared in consistence with the stoichiometricformulae (A_(1-x) B_(x))_(y) Cu_(z) O₂, where A is one or more elementsof Group IIIa of the Periodic Table, e.g., the rare earth elements, B isone or more elements of Group IIa of the Periodic Table, e.g., thealkaline earth metals including beryllium and magnesium, and x=0 to 1;y=2.0 to 4.0, preferably 2.5 to 3.5; z=1.0 to 4.0, preferably 1.5 to3.5; and w=4.0 to 10.0, preferably 6.0 to 8.0. Also, superconductingceramics for use in accordance with the present invention may beprepared consistent with the stoichiometric formulae (A_(a-x) B_(x))_(y)Cu_(z) O_(w), where A is one or more elements of Group Vb of thePeriodic Table such as Bi, Sb and As, B is one or more elements of GroupIIa of the Periodic Table, e.g., the alkaline earth metals includingberyllium and magnesium, and x=0.3 to 1; y=2.0 to 4.0, preferably 2.5 to3.5; z=1.0 to 4.0, preferably 1.5 to 3.5; and w=4.0 to 10.0, preferably6.0 to 8.0. Examples of this general formula are BiSrCaCu₂ O_(x) and Bi₄Sr₃ Ca₃ Cu₄ O_(x). Tc onset and Tco samples confirmed consistent withthe formula Bi₄ Sr_(y) Ca₃ Cu₄ O_(x) (Y is around 1.5) were measured tobe 40 to 60K, which is not so high. Relatively high criticaltemperatures were obtained with samples conforming to the stoichiometricformulae Bi₄ Sr₄ Ca₂ Cu₄ O_(x) and Bi₂ Sr₃ Ca₂ Cu₂ O_(x). The numberdesignating the oxygen proportion is 6 to 10, e.g. around 8.1.

What is claimed is:
 1. A method for forming an improved superconductingoxide material comprising the steps of placing a superconducting oxidematerial into a plasma generating chamber, and oxygen annealing thesuperconducting oxide material by subjecting it to an activated oxygentreatment in which one of oxygen and oxide gas is introduced andactivated by converting it to plasma while simultaneously applying amagnetic field to said material to thereby increase the rate of saidannealing step.
 2. The method of claim 1, wherein the plasma, at apressure of 1 to 800 torr, produces mixed cyclotron field resonance inwhich the electric field and magnetic field interact with each other,and said material is positioned in the mixed cyclotron resonance space.3. The method of claim 1, wherein the superconducting material has thechemical formula (A_(1-x) B_(x))_(y) Cu_(z) O_(w), where x is 0.1 to 1,y is 2.0 to 4.0, z is 1.0 to 4.0, w is 4.0 to 10.0, A is at least oneelement selected from the group of Y (yttrium), Gd (gadolinium), Yb(ytterbium), Eu (europium), Tb (terbium), Lu (lutetium), Sc (scandium)and other lanthanoids, and B is at least one element selected from thegroup of Ba (barium), Sr (strontium) and Ca (calcium).
 4. The method ofclaim 1 where said oxide superconducting material is a copper oxidesuperconducting material.
 5. A method of forming superconducting copperoxide ceramic materials comprising the steps of:disposing asuperconducting copper oxide based ceramic material in a vacuum chamber;introducing a reactive gas comprising oxygen into said vacuum chamber;inputting energy to said reactive gas in order to product a plasma ofoxygen; applying a magnetic field to said superconducting material inthe atmosphere of said plasma.
 6. The method of claim 5, wherein saidapplying step is carried out at an elevated temperature.
 7. The methodof claim 5, wherein the energy applied to the reactive gas iselectromagnetic radiation having a frequency of between about 500 MHz to10 GHz.